The present invention relates to machinery for performing an operation on a workpiece, and more particularly to a mechanism for installation on such machinery for determining the position of the work-performing component of the machinery.
A milling machine or the like typically includes a spindle adapted to receive a work-performing tool. The machine is operated such that the spindle and tool are rotated, and may be moved toward and away from a workpiece by use of a manually-operated lever or handle. Movement of the handle causes the rotating spindle and tool to move in a certain direction, typically vertically, and to come into contact with the workpiece to perform an operation thereon, such as boring a hole or the like.
During operation of the machine, it is desirable for the operator to know the precise location of the rotating tool relative to the workpiece. This ensures that th correct penetration of the tool into the workpiece is obtained. Provision of an accurate indication of the tool position allows the operation to be carried out with precision.
The milling machine typically includes a manually operable tool penetration controlling mechanism for controlling the depth of tool penetration into the workpiece. This manually operated mechanism generally includes a position indicating collar mounted so as to surround a threaded rod. The collar is interconnected with the lever or handle for indicating the depth of penetration of the tool. The internal workings of the machine are designed so that the collar moves synchronously with, and in response to, movements of the spindle and its associated tool. A stop mechanism is provided for limiting the movement of the collar past a certain point. The stop mechanism generally includes a shouldered nut threadedly engaging the threaded rod, and movable along the length of the rod. After placement of the shouldered nut to the desired position, the lever is operated to allow the tool to penetrate the workpiece. Upon engagement of the position indicating collar with the shouldered nut, further penetration of the tool into the workpiece is prevented. This system provides tool penetration control, but is limited by the accuracy of the stop mechanism.
The present invention is intended to provide a more precise mechanism for ascertaining the exact position of the work-performing tool of the machine. In accordance with the invention, a position indicating mechanism includes a linear position indicator means mounted to the machine for providing an indication of the linear position of the work-performing component, such as the spindle and its associated tool. The position indicator means includes an elongated rail and a position indicating scale slidably mounted thereto. The scale is adapted to provide a highly accurate digital readout of its position along the length of the rail. A rail mounting means is provided for affixation to the ends of the rail for rigidly mounting the rail to the machine. A scale mounting means is provided for mounting the position indicating scale to the position indicating collar, which is synchronously movable with the work-performing component of the machine. Therefore, when the handle of the machine is moved so as to raise or lower the work-performing component of the machine, such as the rotating tool, and the position indicating collar moves synchronously therewith, the slidable scale of the position indicating means moves along the rail accordingly to provide an accurate indication of the linear position of the tool. In one embodiment, the scale mounting means comprises a bracket adapted for mounting on the machine to position the scale adjacent the collar. The bracket is provided with means for mounting the scale thereto. The scale mounting means comprises a mounting plate fixedly connected to the scale, and adapted for connection to the movable collar. In this manner, with each component of the position indicating scale mounted to the milling machine, the scale moves slidably along the rail in response to movement of the collar which moves synchronously with the spindle and tool, to provide an accurate indication of the amount of movement of the spindle and tool.